|Publication number||US6937007 B1|
|Application number||US 10/408,490|
|Publication date||Aug 30, 2005|
|Filing date||Apr 7, 2003|
|Priority date||Apr 7, 2003|
|Publication number||10408490, 408490, US 6937007 B1, US 6937007B1, US-B1-6937007, US6937007 B1, US6937007B1|
|Inventors||David J. Ruether, Joseph J. Schottler|
|Original Assignee||Sauer-Danfoss Inc.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (12), Non-Patent Citations (1), Referenced by (2), Classifications (10), Legal Events (5)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The present invention relates to balancing permanent magnets for use as a control input for a Hall effect sensing device. In general, a Hall effect sensing device senses the intensity of a magnetic field at a particular point in space. The intensity of the magnetic field is the flux density of the magnetic field.
The flux density produced by a magnet at a particular point in space is affected by numerous factors, including magnet length, shape, material, and cross sectional area. In order to accurately indicate the position of a control input magnet within a Hall effect sensor device, it is important that the magnet have a predictable magnetic flux density from pole to pole. In our application the predictability only requires them to be symmetrically balanced. This balancing is most necessary where the control input magnet is in a null or non-indicating position relative to the device sensors. Variance in the magnetic flux density from pole to pole while in the null position may give an erroneous reading indicating a false or moved position of the magnetic control input.
It is therefore a principal object of this invention to provide a method of balancing the magnetic flux density of a permanent magnet.
These and other objects will be apparent to those skilled in the art.
A method of balancing the magnetic flux density on a permanent magnet includes defining a physical center on the magnet, operatively aligning the magnet with a plurality of Hall effect sensors, sensing the magnetic flux density along the magnet, and selectively removing a portion of the magnetic material from the side where the pole of the magnet with the greatest magnetic flux density thereby changing both the overall shape and the localized cross-sectional area. This process continues until the magnetic flux density of the permanent magnet is balanced between the two magnetic poles with respect to the defined center.
The present invention will be described as it applies to its preferred embodiment. It is not intended that the present invention be limited to the preferred embodiment. It is intended that the invention cover all modifications and alternatives that may be included within the spirit and scope of the invention.
A sensor reading is taken by the Hall effect sensors 18 to determine the magnetic flux density of various points on the permanent magnet. The reading of the magnet by the Hall effect sensors is made by standard methods. If one magnetic pole 12 or 14 of the magnet 10 is determined to have stronger magnetic flux density than the other pole 12 or 14, a planing tool 20 or 22 is applied to the stronger flux pole to remove a small amount of material from that pole. After the removal of the material, the magnet 10 is again tested, and another Hall effect sensor 18 reading is taken, and process of identifying the stronger flux pole 12 or 14 and removing material is repeated until the Hall effect sensor reading indicates that the magnetic flux densities of the two magnetic poles 12 and 14 is balanced to within a pre-determined degree or variance.
In a second embodiment, greater accuracy of the testing Hall effect sensors 18 may be obtained by moving the permanent magnet 10 within the sensing range of the sensors.
The permanent magnet 10, having been magnetically balanced, is then ready for conventional installation as an input device for a Hall effect sensor in a switch in a joystick controlling heavy equipment.
In application, the balanced magnet is installed as the magnetic control input in a control device on a joystick controlling heavy machinery. The magnet is installed as a control input in a mass produced control device. Balancing of the magnetic flux density in such application is important so that the control device will be stable in the null position, or the position where there should be no movement. An unbalanced magnet inherently creates a danger that the sensors in the control device will interpret the unbalanced condition of the magnet to be an indication of that the control device is in a non-null or moving position. The result from this type of false reading could be to move the heavy equipment when it should be at rest. By using consistently balanced permanent magnets in the control devices in this application, an operator is assured of a consistent reading of the magnet by the control device to correctly indicate the proper position of the control input magnet, particularly when the control device should indicate the null or non-moving position.
Whereas the invention has been shown and described in connection with the preferred embodiments thereof, it will be understood that many modifications, substitutions, and additions may be made which are within the intended broad scope of the following claims. From the foregoing, it can be seen that the present invention accomplishes at least all of the stated objectives.
It is therefore seen that this invention will achieve at least all of its stated objectives.
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|Citing Patent||Filing date||Publication date||Applicant||Title|
|US7088096 *||Nov 14, 2005||Aug 8, 2006||Cts Corporation||Combination hall effect position sensor and switch|
|US20060061353 *||Nov 14, 2005||Mar 23, 2006||Cts Corporation||Combination hall effect position sensor and switch|
|U.S. Classification||324/205, 335/302, 324/202|
|International Classification||H01F7/02, G01N27/74, H01F41/02, G01R33/12|
|Cooperative Classification||H01F41/0253, H01F7/0278|
|Jun 20, 2003||AS||Assignment|
Owner name: SAUER-DANFOSS INC., IOWA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:RUETHER, DAVID J.;SCHOTTLER, JOSEPH J.;REEL/FRAME:014188/0594
Effective date: 20030403
|Sep 23, 2008||FPAY||Fee payment|
Year of fee payment: 4
|Apr 15, 2013||REMI||Maintenance fee reminder mailed|
|Aug 30, 2013||LAPS||Lapse for failure to pay maintenance fees|
|Oct 22, 2013||FP||Expired due to failure to pay maintenance fee|
Effective date: 20130830